In two experiments, 216 college students learned a mathematical procedure and returned for a test either one or four weeks later. In Experiment 1, performance on the four-week test was virtually doubled when students distributed 10 practice problems across two sessions instead of massing the same 10 problems in one session. This finding suggests that the benefits of distributed practice extend to abstract mathematics problems and not just rote memory cognitive tasks. In Experiment 2, students solved 3 or 9 practice problems in a single session, but this manipulation had no effect on either the one-week or four-week test. This result is at odds with the virtually unchallenged support for the strategy of continuing practice beyond the point of mastery in order to boost long-term retention. The results of both experiments suggest that the organization of practice problems in most mathematics textbooks is one that minimizes long-term retention. One appendix is included. (Contains 1 figure.) [This article was published in: "Applied Cognitive Psychology," 20, 1209-1224, 2006.]